Catheter distal end made of plastic tube and flexible printed circuit boards

ABSTRACT

A catheter includes an insertion tube, a flexible substrate and one or more electrical devices. The insertion tube is configured for insertion into a patient body. The flexible substrate is configured to wrap around a distal end of the insertion tube and includes electrical interconnections. The electrical devices are coupled to the flexible substrate and are connected to the electrical interconnections.

FIELD OF THE INVENTION

The present invention relates generally to catheter distal ends, andparticularly to distal ends made of a flexible substrate.

BACKGROUND OF THE INVENTION

Catheters may be used in various medical applications, such ascardiology. For example, U.S. Patent Application Publication2015/0157400, whose disclosure is incorporated herein by reference,describes a device positionable in a cavity of a bodily organ (e.g., aheart) that may discriminate between fluid (e.g., blood) and non-fluidtissue (e.g., wall of heart) to provide information or a mappingindicative of a position and/or orientation of the device in the cavity.The device may include a plurality of transducers, intravascularlyguided in an unexpanded configuration and positioned proximate thenon-fluid tissue in an expanded configuration. Expansion mechanism mayinclude helical member(s) or inflatable member(s).

U.S. Pat. No. 7,881,769, whose disclosure is incorporated herein byreference, describes a catheter for performing a medical operation on anorganic lumen. The catheter includes an elongated member, a medicaloperational element located at a distal end of the elongated member, anelectromagnetic field detector located at the distal end, and a wiringfor coupling the electromagnetic field detector with a medicalpositioning system, wherein the medical positioning system determinesthe position and orientation of the distal end.

U.S. Patent Application Publication 2010/0049191, whose disclosure isincorporated herein by reference, describes an electromagnetic energydelivery device which is deployable through an elongate channelextending along a flexible endoscope for delivering electromagneticenergy to tissue. The device has an elongate main body and an electrodeassembly at a distal end of the device. The main body of the device isflexible along the length of the device to enable the device to conformto the shape of a channel of a flexible endoscope.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a catheter including aninsertion tube, a flexible substrate and one or more electrical devices.The insertion tube is configured for insertion into a patient body. Theflexible substrate is configured to wrap around a distal end of theinsertion tube and includes electrical interconnections. The electricaldevices are coupled to the flexible substrate and are connected to theelectrical interconnections.

In some embodiments, the insertion tube is made of plastic. In someembodiments, the insertion tube is hollow so as to form an internallumen for leading one or more electrical wires to the distal end. In anembodiment, the insertion tube is hollow so as to form an internal lumenfor leading one or more irrigation tubes to the distal end.

In a disclosed embodiment, the flexible substrate includes a flexibleprinted circuit board (PCB), and the electrical interconnections includeconductive traces. In an embodiment, the flexible substrate includes oneor more films that plate the distal end so as to form at least some ofthe electrical interconnections and the electrical devices. In anotherembodiment, the flexible substrate is perforated so as to formirrigation holes.

In an embodiment, the electrical devices include one or more electrodes.Additionally or alternatively, the electrical devices may include one ormore thermocouples. Further additionally or alternatively, theelectrical devices may include one or more thermistors. Furtheradditionally or alternatively, the electrical devices may include one ormore pressure sensors. Further additionally or alternatively, theelectrical devices may include one or more position sensors.

In some embodiments, the flexible substrate includes a sheet havingfirst and second edges, and a dome-cover, the sheet is configured towrap around the distal end of the insertion tube, and the dome-cover isconfigured to cover an apex of the distal end. In an embodiment, thesheet and the dome-cover are made of a single contiguous section of theflexible substrate. In another embodiment, the first and second edges ofthe sheet are welded to one another when wrapped around the distal end.In yet another embodiment, the dome-cover is glued to the apex of thedistal end. In still another embodiment, the dome-cover is made of aliquid crystal polymer (LCP) PCB, which is configured to be formed intoa cup shape, and the cup shape is configured to be bonded to the apex ofthe distal end.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method for producing a catheter. The methodincludes providing an insertion tube, and wrapping a flexible substratearound a distal end of the insertion tube. The flexible substrateincludes one or more electrical interconnections. One or more electricaldevices are coupled to the flexible substrate, and the electricaldevices are connected to the electrical interconnections. The presentinvention will be more fully understood from the following detaileddescription of the embodiments thereof, taken together with the drawingsin which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, pictorial illustration of a catheterizationsystem, in accordance with an embodiment of the present invention;

FIGS. 2 and 3 are schematic, exploded pictorial illustrations of adistal end assembly of a catheter, in accordance with an embodiment ofthe present invention; and

FIG. 4 is a schematic, pictorial illustration of a distal end assemblyof a catheter, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS Overview

Medical probes such as catheters are used in a variety of therapeuticand diagnostic medical procedures, for example in cardiac ablation.Catheter distal ends are often multi-functional and comprise a largenumber of elements such as different types of electrodes, electricalinterconnections for the electrodes, irrigation tubes and holes. Thedistal end is typically limited in size, this limits the functionalitythat can be incorporated therein.

Embodiments of the present invention that are described hereinbelowprovide improved distal end assembly configurations for medical probes,which overcome the above limitations. In some embodiments, the distalend assembly is fabricated from a single sheet of a flexible substratethat provides various functionalities within a small volume such as: (i)forms a mechanical substrate for mounting or embedding electricaldevices such as electrodes or sensors, (ii) comprises conducting tracesthat convey electrical signals to/from the electrical devices, and/or(iii) comprises irrigation tubes and holes for irrigating the tissuearea. The disclosed techniques further describe methods for producingthese catheter distal ends.

The distal end assembly typically comprises a cylindrical insertion tubehaving a cover on its top. In some embodiments, the insertion tubecomprises an inner skeleton structure and the cylindrical shape of thetube is formed by wrapping a sheet of flexible substrate, such as amulti-layered printed circuit board (PCB), around the skeletonstructure.

In some embodiments, at least some of the electrical wiring of thedistal end is implemented using circuit traces in or on the flexiblePCB. The traces are configured to electrically connect the electricaldevices coupled to the PCB (e.g., electrodes or sensors) to wiring thattraverse the catheter. Some types of electrical devices (e.g.,thermocouples) may be embedded between the PCB layers. Other devices,such as micro-electrodes, may be mounted on the PCB surface before orafter wrapping the PCB around the insertion tube. In other embodiments,the PCB may be perforated so as to form irrigation holes.

In an embodiment, the PCB comprises a sheet having two edges, and adome-cover. The sheet is configured to wrap around the skeletonstructure of the insertion tube and the two edges are attached to oneanother by welding or using any other suitable coupling technique. Insome embodiments, the dome-cover may be glued to the apex of the distalend assembly and may comprise irrigation holes and one or moretip-electrodes mounted thereon. In alternative embodiments, thedome-cover may be fabricated from a liquid crystal polymer (LCP) PCB,which may be thermoformed into a cup shape and bonded to the apex. Thesheet and the dome-cover may be formed as a single contiguous piece ofthe PCB, or as separate parts that may be coupled to one another afterbeing wrapped around the distal end assembly.

In an alternative embodiment, the distal section of the insertion tubeis contiguous, and the conductive traces and electrical devicesdescribed above are formed by directly plating one or more films aroundthe insertion tube. At least the outermost film is typicallybiocompatible so as to allow direct physical contact between the distalend assembly and the heart. In some embodiments, the insertion tube aswell as the flexible substrate may be perforated, so as to allowirrigation flow to exit the insertion tube via the irrigation holes.

The disclosed techniques help to increase the functionality of medicalcatheters without compromising size, as well as achieve smallercatheters for new applications. Furthermore, using very large integratedcircuit (VLSI) techniques provides producers of the flexible substrateswith high flexibility to improve the catheters and to reduce the cost ofthe distal end. For example, the disclosed techniques enable integrationof all electrical devices and interconnections in a flexible substratewrapped around a low cost molded plastic assembly rather than producingexpensive micro-machined metal tubes, wires and electrodes, and mountingthem on the metal tube.

System Description

FIG. 1 is a schematic, pictorial illustration of a catheterizationsystem 20, in accordance with an embodiment of the present invention.System 20 comprises a probe 22, in the present example a cardiaccatheter, and a control console 24. In the embodiment described herein,catheter 22 may be used for any suitable therapeutic and/or diagnosticpurposes, such as ablation of tissue in a heart 26.

Console 24 comprises a processor 42, typically a general-purposecomputer, with suitable front end and interface circuits for receivingsignals from catheter 22 and for controlling the other components ofsystem 20 described herein.

An operator 30 (such as an interventional cardiologist) inserts catheter22 through the vascular system of a patient 28 lying on a table 29.Catheter 22 comprises a distal end assembly 40, which is depicted indetails in FIGS. 2-4. Operator 30 moves assembly 40 in the vicinity ofthe target region in heart 26 by manipulating catheter 22 with amanipulator 32 near the proximal end of the catheter as shown in theinset of FIG. 1. The proximal end of catheter 22 is connected tointerface circuitry in processor 42.

In some embodiments, the position of the distal end assembly in theheart cavity is typically measured by magnetic position sensing incatheter tracking system 20. In this case, console 24 comprises a drivercircuit 34, which drives magnetic field generators 36 placed at knownpositions external to patient 28 lying on table 29, e.g., below thepatient's torso.

FIG. 2 is a schematic, exploded pictorial illustration of distal endassembly 40, in accordance with an embodiment of the present invention.In some embodiments, distal end assembly 40 comprises an internal member69, which may be made of plastic or any other suitable material. Theinternal member is also referred to herein as an insertion tube. Theinternal member may have a skeleton support structure as depicted inFIG. 2, or any other suitable structure as will be described in otherembodiments below.

A base 58 is located at the proximal end of member 69, a ring-shapeddome-support 68 is located at the apex of member 69, and multiple ribs56 connect the base and the dome-support. In this embodiment, member 69has an internal lumen for directing irrigation into the inside of cavityformed by flexible printed circuit board (PCB) sheet 60.

Distal end assembly 40 further comprises a flexible substrate, such as amulti-layered flexible printed circuit board (PCB) sheet 60, which isconfigured to wrap around member 69. In an embodiment, after wrapping,the left and right edges of sheet 60 may be coupled to one another bywelding or using any other suitable coupling technique. In someembodiments, one or more electrical devices may be mounted on PCB sheet60, as will be depicted in FIG. 3 below.

PCB sheet 60 typically comprises electrical interconnections, such asconductive traces (not shown), which are configured to electricallyconnect the electrical devices coupled to the PCB to suitable wires thattraverse the catheter, or to other suitable circuitry. In someembodiments, PCB sheet 60 may be perforated so as to form one or moreirrigation holes 64, which are configured to allow irrigation fluid toflow out the insertion tube when irrigating the tissue of heart 26, forexample during an ablation procedure.

Distal end assembly 40 further comprises a dome-cover 66, which isfabricated from a flexible PCB and configured to wrap arounddome-support 68. In some embodiments, dome-cover 66 may be glued todome-support 68. In alternative embodiments, cover 66 may be fabricatedfrom a liquid crystal polymer (LCP) PCB, which may be formed (e.g.,thermoformed) into a cup shape and bonded to sheet 60. The cup shape maybe bonded to dome-support 68 and sheet 60 bonded to base 58 using anysuitable bonding technique known in the art.

In some embodiments, sheet 60 and cover 66 are made from a single pieceof contiguous PCB or any other suitable flexible substrate. Inalternative embodiments, sheet 60 and cover 66 may be formed fromseparate pieces of material and coupled to one another using welding orany other suitable coupling technique.

FIG. 3 is a schematic, exploded pictorial illustration of distal endassembly 40, in accordance with an embodiment of the present invention.FIG. 3 shows the opposite surfaces of sheet 60 and cover 66 from thoseshown in FIG. 2. In some embodiments, sheet 60 may comprise one or moremicro-electrodes 62, which are configured to read signals and impedance.Cover 66 is intended to face internal tissue of heart 26 during theablation procedure. In some embodiments, one or more thermocouples (notshown) may be embedded between the layers of PCB sheet 60. Thethermocouples may be formed using PCB manufacturing techniques such assputtering or be prepared in advance and embedded between the layers ofsheet 60.

In an embodiment, cover 66 may comprise tip electrode 71, which isconfigured to ablate the internal tissue of heart 26. In someembodiments, cover 66 may comprise non-metallized plastic parts 70formed on the PCB between sections of tip electrode 71. In anembodiment, parts 70 may be perforated so as to assist in bondingplastic parts 70 to the PCB.

Additionally or alternatively, distal end assembly 40 may comprise oneor more position sensors that enable the magnetic position trackingsystem to measure and track its location in the body.

In the present context, tip electrode 71, micro-electrodes 62 and thethermocouples, thermistors and position sensors are regarded as examplesof electrical devices coupled to the flexible substrate of the distalend assembly. In alternative embodiments, any other suitable types ofelectrical devices can be used, such as pressure sensors.

In some embodiments, micro-electrodes 62 and tip electrode 71 may beprinted directly on PCB sheet 60 and on dome-cover 66, respectively. Inalternative embodiments, at least some of the electrodes (e.g.,micro-electrodes 62) may be mounted, for example, on sheet 60 on eitherthe inside or the outside and bonded to the electrical interconnections.The electrical devices may be electrically connected to console 24 viathe electrical interconnections comprised in sheet 60 and cover 66, andthe wiring traversing catheter 22.

FIG. 4 is a schematic, pictorial illustration of distal end assembly 40,in accordance with an embodiment of the present invention. PCB sheet 60and dome-cover 66 are wrapped around member 69 so that irrigation holes64 and the electrical devices, such as micro-electrodes 62 and tipelectrode 71, are facing the internal tissue of heart 26.

The configuration of distal end device 40 shown in FIGS. 2-4 is anexample configuration that is chosen purely for the sake of conceptualclarity. In alternative embodiments, any other suitable configurationcan be used. For example, the flexible substrate used for implementingthe distal end device may comprise any other suitable substrate, notnecessarily a PCB.

In alternative embodiments, rather than having a skeleton shape, thedistal end assembly comprises a contiguous hollow insertion tube made ofplastic or any other suitable material, and having a cap at its distaltip. The insertion tube is configured to form an internal lumen forleading electrical wires and/or irrigation tubes via catheter 22. Inthis embodiment, at least some of the electrical interconnections andinsulating films described above may be disposed as a flexible substratedirectly onto the insertion tube, using plating or any other suitabledisposing techniques.

At least one of the disposed films (e.g., the outermost film) may bebiocompatible so as to allow direct physical contact between the distalend assembly and the heart tissue. Furthermore, the electrodes or otherelectrical devices may be directly plated on the insertion tube, orcoupled to the tube after forming the electrical interconnections. In anembodiment, the insertion tube may be perforated so as to form theirrigation holes using very large scale integration (VLSI) processesknown in the art, such as deposition (e.g., sputtering, physical vapordeposition (PVD) and plating), patterning (e.g., direct deposition onmasks or photo-lithography and etching) and/or laser drilling forperforating the irrigation holes in the insertion tube.

Although the embodiments described herein mainly address ablationcatheters, the methods and systems described herein can also be used inany other suitable medical probe, such as sinuplasty and neurosurgicalprocedures.

It will be appreciated that the embodiments described above are cited byway of example, and that the present invention is not limited to whathas been particularly shown and described hereinabove. Rather, the scopeof the present invention includes both combinations and sub-combinationsof the various features described hereinabove, as well as variations andmodifications thereof which would occur to persons skilled in the artupon reading the foregoing description and which are not disclosed inthe prior art. Documents incorporated by reference in the present patentapplication are to be considered an integral part of the applicationexcept that to the extent any terms are defined in these incorporateddocuments in a manner that conflicts with the definitions madeexplicitly or implicitly in the present specification, only thedefinitions in the present specification should be considered.

1. A catheter, comprising: an insertion tube for insertion into apatient body; a flexible substrate, which is configured to wrap around adistal end of the insertion tube and which comprises electricalinterconnections; and one or more electrical devices, which are coupledto the flexible substrate and are connected to the electricalinterconnections.
 2. The catheter according to claim 1, wherein theinsertion tube is made of plastic.
 3. The catheter according to claim 1,wherein the insertion tube is hollow so as to form an internal lumen forleading one or more electrical wires to the distal end.
 4. The catheteraccording to claim 1, wherein the insertion tube is hollow so as to forman internal lumen for leading one or more irrigation tubes to the distalend.
 5. The catheter according to claim 1, wherein the flexiblesubstrate comprises a flexible printed circuit board (PCB), and whereinthe electrical interconnections comprise conductive traces.
 6. Thecatheter according to claim 1, wherein the flexible substrate comprisesone or more films that plate the distal end so as to form at least someof the electrical interconnections and the electrical devices.
 7. Thecatheter according to claim 1, wherein the flexible substrate isperforated so as to form irrigation holes.
 8. The catheter according toclaim 1, wherein the electrical devices comprise one or more electrodes.9. The catheter according to claim 1, wherein the electrical devicescomprise one or more thermocouples.
 10. The catheter according to claim1, wherein the electrical devices comprise one or more thermistors. 11.The catheter according to claim 1, wherein the electrical devicescomprise one or more pressure sensors.
 12. The catheter according toclaim 1, wherein the electrical devices comprise one or more positionsensors.
 13. The catheter according to claim 1, wherein the flexiblesubstrate comprises a sheet having first and second edges, and adome-cover, wherein the sheet is configured to wrap around the distalend of the insertion tube, and wherein the dome-cover is configured tocover an apex of the distal end.
 14. The catheter according to claim 13,wherein the sheet and the dome-cover are made of a single contiguoussection of the flexible substrate.
 15. The catheter according to claim13, wherein the first and second edges of the sheet are welded to oneanother when wrapped around the distal end.
 16. The catheter accordingto claim 13, wherein the dome-cover is glued to the apex of the distalend.
 17. The catheter according to claim 13, wherein the dome-cover ismade of a liquid crystal polymer (LCP) PCB, which is configured to beformed into a cup shape, and wherein the cup shape is configured to bebonded to the apex of the distal end.
 18. A method for producing acatheter, comprising: providing an insertion tube; wrapping a flexiblesubstrate around a distal end of the insertion tube, wherein theflexible substrate comprises one or more electrical interconnections;and coupling one or more electrical devices to the flexible substrateand connecting the electrical devices to the electricalinterconnections.
 19. The method according to claim 18, whereinproviding the insertion tube comprises providing a plastic tube.
 20. Themethod according to claim 18, wherein providing the insertion tubecomprises providing a hollow insertion tube so as to form an internallumen for leading one or more electrical wires to the distal end. 21.The method according to claim 18, wherein providing the insertion tubecomprises providing a hollow insertion tube so as to form an internallumen for leading one or more irrigation tubes to the distal end. 22.The method according to claim 18, wherein wrapping the flexiblesubstrate comprises wrapping a flexible printed circuit board (PCB), andwherein the electrical interconnections comprise conductive traces. 23.The method according to claim 18, wherein wrapping the flexiblesubstrate comprises directly plating the distal end with one or morefilms so as to form the electrical interconnections and the electricaldevices.
 24. The method according to claim 18, and comprisingperforating the flexible substrate so as to form irrigation holes. 25.The method according to claim 18, wherein coupling the electricaldevices comprises coupling one or more electrodes.
 26. The methodaccording to claim 18, wherein coupling the electrical devices comprisescoupling one or more thermocouples.
 27. The method according to claim18, wherein coupling the electrical devices comprises coupling one ormore thermistors.
 28. The method according to claim 18, wherein couplingthe electrical devices comprises coupling one or more pressure sensors.29. The method according to claim 18, wherein coupling the electricaldevices comprises coupling one or more position sensors.
 30. The methodaccording to claim 18, wherein wrapping the flexible substrate compriseswrapping a flexible sheet around the distal end of the insertion tube,and covering an apex of the distal end using a dome-cover.
 31. Themethod according to claim 30, wherein the flexible sheet and thedome-cover comprise a single contiguous section of the flexiblesubstrate.
 32. The method according to claim 30, wherein wrapping theflexible sheet comprises welding the first and second edges of the sheetto one another.
 33. The method according to claim 30, wherein coveringthe apex comprises gluing the dome-cover to the apex of the distal end.34. The method according to claim 30, wherein covering the apexcomprises forming the dome-cover into a cup-shape and bonding thecup-shaped dome-cover to the apex of the distal end.
 35. The methodaccording to claim 34, wherein forming the dome-cover comprisesthermoforming a liquid crystal polymer (LCP) PCB.